Hydraulic press for stepwise drawing of metal



R. A. KASER HYDRAULIC PRESS FOR STEP-WISE DRAWING OF IETAL Filed Dec. 11, 1942 l M H w W 6 on u\\\\-\\\ w 3 L in WT! n if1E IR A o a I. u vw m .3 us 7 M w R I z m a y a Z 1 10 A w 5 Z Z Y M B M Z A M a O a H I R L 2 M 5 W M w m o lo 5 ihlentecl 2%,, i94

HYBRAULIKJ PRESS FOR STEPWKSE DRAG 6F METAL Robert A. liaser, Eayton, @hio, assignor to The Hydraulic Development Corporation, Inc... Wilmington, Del, a corporation of Delaware Application December ll, 1942, Serial No. 468,874

(Cl. BN2) 8 Claims.

This invention relates and, in particular, to control mechanism for a reciprocable plunger to control the advancement thereof in steps. The invention may advantageously be used in connection with drawing presses for performing deep drawing strokes.

in ord r to permit step-wise deep drawing on a single press, it has been suggested to arrange in the "base of a crank-type. mechanical press a hydraulic cylinder-.pistcn-assembly and to control the latter so that a die carried thereby and operating with the drawing punch, is lifted by a predetermined distance each time the punch has performed an advancing and a retraction stroke.

To hold the'work piece clamped against the bed during this drawing operation, it has been suggested to provide the mechanical press with a hydraulically operated clamping platen. However, since this type of press requires not only the complete mechanical drawing mechanism, but also a number of parts and control means which are standard equipment with hydraulic presses, the above mentioned hydro-mechanical deep drawing presses are relatively expensive and complicated.

It is, therefore, an object of this invention to provide control means for use in connection with a fluid operable plunger, such as a press ram, which will cause said plunger to, perform to hydraulic machinery a plurality of successive advancing and retracting strokes, while simultaneously causing said plunger to move closer to a fixed point, for invide a hydraulic drawing press in which the press ram is hydraulically advanced in one and the same direction in steps, and in which, following each step, the press ram is retracted by a distance less than the total advancing preceding said retraction stroke.

Still another object or the invention consists in the provision of a drawing press as set forth in the preceding paragraph, in which the distance by which the press ram is being advanced during each step may be. varied.

l ness and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

Fi e 1 illustrates the control mechanism accord ng to the invention in connection with. a hydraulic drawing press.

Figure :1 illustrates the wiring diagram for con 1 means associated with the press shown in e l. route 3 shows a detail of Figure 1.

stroke 2 the drawings comprises a reclprocable element which, in response to a predetermined advancingstroke of the press ram, actuates' a limit switch to thereby initiate the reversal of the press ram.

When pressure fluid is being admitted to the raxn'for retracting the same, a portion of this pressure fluid operates means for actuating said reciprocable element so that the latter, in re sponse to a. predetermined retraction stroke of the ram, less than the preceding advancing stroke thereof, initiates a new advancing stroke of said ram, which new advancing stroke will be larger than the preceding retraction stroke. At the end of this advancing stroke, the reciprocable element again actuates the said limit switch, to thereby initiate a retracting stroke of the ram in the same manner as mentioned before.

The cycle is then repeated until the work piece has been drawn to its desired depth, at which time the press ram is completely retracted to its initial starting position.

Structural arrangement Referring now to the drawings in detail, the system shown therein comprises a press cylinder 5 having reciprocably mounted therein a press ram 2. Connected to the press ram. 2 is a press platen 3 carrying a. punch 4 adapted, in coopera= tion with the die 5, to shape a. work piece, such as a metal sheet 6. Blankholder means "i is prcvided for clamping the marginal portion of metal sheet t against the adjacent portion of the die 5. The clamping means i may be clamped. against the work piece 6 by any standard clamp ing mechanism,

The press platen 8 is provided with an arm adapted to engage a collar 9 adiustably mounted on a push rod H]. The push rod It! has mounted thereon a collar ll adapted to engage a threearm lever 52, which latter is adapted to shift about a pivot l3. The arm M of the lever ii is pivotally connected with an armature it controlled by a. solenoid It in such a manner that energization of the solenoid it causes the armature to move downwardly, thereby shifting the three-arm lever l2 in counter-clockwise direction and causing the linkage ll connected thereto to bring about movement of the pump it into full delivery advancing stroke position. The pump l8 may be a reversible variablcdelivery pump of any standard design and may be either of the radial piston or the radial vane type.

One side of the pump I8 is connected through the conduit [9 with the upper portion of the press cylinder 6, while the other side of the pump it is connected through the conduit 2t with the lower portion of the press cylinder 9. Connected with the conduit 58 is a conduit ti leading to a tonnage control valve 52 of any standard de.

sign which, in response to a predetermined pres sure in the conduit i, closes a normally open 5 switch 5m. (see Figure 2).

Branching ofl from the conduit so is a. pilot I linet2i comprising a check valve 22 adapted to admit pressure fluid from the fluid reservoir or tank 23 into the conduit 2i, while preventnig the flow of fluid in the reverse direction. Branchinglofi from the conduit 2! is a pilot line 2 lead-,

to a surge valve 25. The surge valve is adapted in response to a predetermined pressure 4 the contactor A causes the contactor switch A2 to open and thecontactor switch A2 to close, while deenergization of the contactor A causes the contactor switch Al to close and the contactor switch A2 to' open. When the contactcr switch A2 is closed, it establishes electric connection between the line 55 and the main supply line 53 through the normally closed reset switch 5 60. When thecontactor switch Al and the starter in the conduit 24 to open, thereby establishing fluid-Z connection between the tank 23 and the upper portion of the press cylinder i. The surge valve 25 also opens in response to a suction effect 7 in the upper portion of the press cylinder i.

Connected with the lower portion oi the press cylinder 4 is a further pilot line 26 leading into one end of a control cylinder 2? (see Figure 3), having reciprocably mounted therein a piston 28. The piston 28 is continuously urged into its left hand position, with regard to Figure 3, by a spring 29, having one end in abutment with the switch 51 are closed, the main supply line 53 is connected through lines 58 and 69 and the contactor B with the" main supply line 58.

piston 28, while the other end abuts the right hand wall of the cylinder 27. An exhaust line 30 connects the right hand portion of the cylinder 2'! with the tank 23.

Connected to the left side of the piston 28 is 4 a piston rod 3| carrying an adjustable abutment; nut 32 for abutment with the left side of the cylinder 21. Connected with the right hand side of the piston 28 is a rod 33 carrying a pawl 34 Energization of the contactor B causes the normally open switches Bi and B2 to close. Closure of the switch B2 connects the main supply line 53 with. the solenoid l6, while closure of the contactor switch Bi connects the lines 6% and G2 with each other.

The line 62 is connected through the line 33 with the line 58 and is adapted by closure of the limitswitch-LS! 'to be connected with the main supply line 53 The line 61 is adapted to coin municate through the normally closed switch LS2 with the main supply line 53.

It may beassumcd that the press ram 2 is in its fully retracted position, in which the push rod ill, by means oi the lever i2 and linkage ll, holds thepump II in substantially neutral or no delivery position.

It may also be assumed that the work piece is properly clamped betweenthe blansholder means v1 and the adjacent portion of the die If it is now desired to perform a deep drawing stroke, the operator closes the; starter switch 51, therebyclosing the energizing circuit for the contactor Bthrough the normallyclosed con- I tactor switch Ai. Energization oithecontactor keyed thereto, is a rod 36 forming an extension of the spindle 31, which latter has addustably mounted thereon a collar 38 for cooperationvwith J a. normally closed limit switch LS2. The collar 38 is adapted to engage and thereby to open'the f limit switch LS2. The rod 36 is adapted toacn-e gage and close the normally open limit switch LS1. The spindle 31 threadedly engages nut portions 39 and so connected to a slide, whichis slidably mounted on and guided-by a stationary B causes the contactor switches Bland B2 to close. Closure of the contactor 'switch Bi establishes a holding circuit for the contactor B, which holding circuit comprises the main supply line 53, normally 'closed limit switch LS2,now closed switch Bi, lines 62, ll, 58, switch Al, contactcr B and the main supply line- 56. The contactcr is, therefore, remains energized when the switch 51, after its 'relcasefb'y the operator, again opens.

guide 42. The nut portions 39 and so are adapt-- ed alternately to be engaged by the .platen arm 8a. The spindle a? is furthermore provided with a keyway d3 engaged by a key (not shown), which key is provided in the beveled gear 54 for con 1 necting the same with the spindle 31, so that" rotation, of

,The' spindle 3i has also adiustably mounted thereon a collar 68 engaged by the upper portion of a springdt, the lower portion of which is supported by ja support 5G. The spring is flcatingly supports the spindle iii.

Referring now to the wiring diagram of Figure v 2, the some shows the main supply line 58 con nected with the line 5 3, which latter is adapted, by closure of the tonnage control switch 5211 through line and contactor A to be connected with the main supply line 55. Energization of the gear Fit 'willrotate the spindleTj'}v 3?. The spindle, 3'8 is: slidable' in the gear 451 The beveiedgear Ad is engaged by a beveled gear? d5 ,which latter is rotated by means of the hand wheel es, and is iournalled in an extension e'i of'the guide 52. 4

pressure begins to build up in the upper oi the ram 2;the fluid delivered by the gin -Closure 'oi gtheflcontactor switch B2 closes the energizing circuit for the solenoid it, so that latter moves the armature l5 downwardly throughthellever l2 andlinkage ii, shifts the pump f8 into forward delivery position. Fressure r'luid'iroinfithe pump l8, therefore, flows through conduitflginto the upper portion or the i, while iiuid from the lower portion of the eylin der I is withdrawn through conduit is. r

'2, thereioramoves downwardly by gravity as fast asfl'uid is: withdrawn from the lower portion of the press cylinderfi.

During the first portion of the downward 68 through the conduit, is is supplemented fluid passing'from the tank 23 through i: valve 25, which latter isopen at this 3in to the suction eflect created in the upper oi the press cylinder i.

When the punch l engages the work of the cylinder 1,. causing the surge valve close. The ram 2 now begins its actual d stroke.

When the punch i has moved downw predetermined distance, the arm as ens" nut portion 46. Further downward mov aeiaees the punch 4 to a position indicated by the dotdash line 64, has caused the spindle 31 to move downwardly to such an extent that the collar; 88 has opened the limit switch LS2. Opening of the limit switch LS2 breaks the holding circuit for the contactor B, so that the contactor switches Bi and B2 open. Opening of the contactor switch I Bi has no additional effect at this time.

Opening of the contactor switch B2 causes deenergization of the solenoid 56, so that a, spring (not shown), which is provided in the servomotor 65 associated with the pump it, causes the pump 48 to move into its full delivery retraction stroke position. Consequently, pressure fiuid delivered by the pump i8 now passes through the conduit 20 into the lower portion of the cylinder l, while simultaneously opening the surge valve 25, The ram 2, therefore, begins to move upwardly.v Pressure fluid admitted to the lower portion of the press cylinder i is also conveyed through the pilot line 28 into the left hand portion of the cyl inderzi, where it acts upon the piston 28 and causes the same to move the rod 33 and the pawl 34 toward the right. This movement of the pawl 3% causes the ratchet 35 to rotate in anti-cloclzwise direction, with regard to Figure 3, so that the spindle 3'? performs a corresponding rotation This rotation or the spindle 31 causes the slide 4! to move downwardly a predetermined distance.

When the platen arm 8a, during the upward movement of the ram 2 just described, engages the nut portion 39, it begins to lift the spindle pressure fluid to the lower Portion of the tactor switches El and B2 to open. opening of the contactor switch Bi has no at this time, the opening oiithe contaetor B2 causes denergization oi the solenoid it that the spring, previously referred to in the serve motor 85, causes the pump li to move into ital delivery retraction stroke position. the Jr is her described above, the pump now de M cylinder i and causes the press ram 2 to move upwardly. I v

Inasmuch as the contactor A remains energized and, therefore, the contactor switch at remains of its retraction stroke, the push rod 31 and, thereby, also the extension rod 86. 7 When the spindle 3i has been lifted a predetermined distance, the rod 36 closes the limit switch LS5. Closure of the limit switch LSi establishes an energizing circuit for the contgctor B, which circuit comprises the main supply line 53, now closed switch LS5, lines 63 and 88, ccntactor switch Al, line 59, contactor B and the main supply line 56.

Consequently, the contactor B is energized and again closes the contactor switches BI and B2, with the result that, as described above, the solehold it is energized. 1

As likewise described above, energization of the solenoid it shifts the pump it again on forward stroke and the ram 2 again moves downwardly. Since, however, as mentioned above, the slide ll was moved downwardly from the position it pre- I viously occupied, the platen arm to will not ongage the nut portion to at the same point at which it previously engaged the said nut portion, but will have to travel. further downwardly before it again engages said nutportion 5d and thereby,

" in the same manner as described above, initiates another partial retraction stroke of the ram 2. The cycle described above is then successively repeated through the stages indicated in dot.

dash lines fit, d?! and $3.

I ,"When the punch d has reached the position corresponding to the dot dash line t5, the work piece s has been drawn to its desired shape and the pressure now developed in the upper portion oi the press cylinder 3 and conveyed through the conduit ii: to the tonnage control valve 52, causes the tonnage control switch 52a to close. As a result thereof, the contactor A is energized. Closure ol the contactor A causes the contactor switch at to open and the contactor switch at to close.

' filosure oi the contactcr switch A2 establishes an energizing circuit for the contactor A, where as opening of the contactor switch At breaks the energizing circuit for the contactor 3. Beenergization of the contactcr B causes the con= plunger having advancing and retracting in actuating fluid to said advancing means or o open, the contactor B will not be energhed when the spindle 3?, during the present upward mov" ment of the ram 2,is lifted and causes the rod to close the limit switch LS i When the press ram 2 has reached the end shifted the lever 52 into such a position the linkage i'i has moved the pump it into sue stantially neutral or no delivery position. Con

sequently, no fluid is conveyed to or withdrawn from the press cylinder 3 and the ram 2 comes to a stop. To restore the previous position, the operator resets the spindle 3? by rotating the hand wheel 56. Thereafter, the reset switch 8c is term pcrarily opened to de=energize the contactor is. All the parts are now at their initial position and, after replacement of the workpiece, a new work cycle may be started.

It will be understood that I desire to com prehend within my invention such modifications as come within the scope of the claims.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is: a

lfiin a hydraulic system; a reoiprocahle plunger having advancing and retracting rneana,

first and second control means operable to direct actuating fluid to said advancing means or to said retracting means, respectively; a pair or" spaced means operated respectively by said plunger at the end of the retraction stroke and at the end of the advancing stroke for automati= cally making first one and thenthe other oi said control means effective for autoniaticaiiy reci eating said plunger between predetermined its; and means operated by the supply of fluid said'retracting means for adjusting both oi said spaced means a predetermined distance in advancing direction,

2. In a hydraulic system; a reciprocabie first and second control means operable to said retracting means, respectively; spa.

means operated by said plunger for automatically 1 actuating first one and then the other oi amazes spaced means operated respectively by said plunger at the end of the retraction stroke and at the end of the advancing stroke for automatically making first one and then the other of said control means efiective for automatically reciprocating said plunger between predetermined limits; means operated by the supply of fluid to said retracting means for adjusting both of said spaced means in the advancing direction a predetermined amount ior continuously shifting said predetermined limits in said advancing direction;

and means selectively operable initially to adjust said spaced means.

4. In a hydraulic system; a reciprocable plungser having advancing and retracting means; a fluid source for supplying said means; control means associated with said source operable to direct the delivery thereof to said advancing or to said retracting means; first means adapted for operation by said plunger at a predetermined point in its advancing travel for actuating said control means to bring about the supply of fluid to said retracting means; second means operated by said plunger at a predetermined point in its retracting movement-for actuating said control means to bring about the supply of fluid to said advancing means; a threaded spindle supporting both of said first and second means rotatable simultaneously to adjust the position of said means; manual means for rotating said spindle; and means operable in response to the supply of actuating fluid to saidretracting means for rotatingsaid spindle a predetermined amount.

5. In a hydraulic system; a reciprocable plunger having advancing and retracting means; first and second control means operable to direct actuating fluid to said advancing means or to said retracting means, respectively; a threaded rod yieldably supported parallel with the path of said plunger; spaced cooperating abutment means carried by said plunger and by said threaded rod for moving said rod in response to predetermined movements of said plunger in opposite directions;

first switch means adapted for operation by said rod when the latter moves upwardly for actuattrol means; manually operable means for turning saidrod initially to position the abutment means carried thereby; and fluid pressure responported adjacent said plunger and parallel to the path thereof; spaced abutment means carried by said rod; an abutment carried by said plunger adapted for engaging said spaced abutment means; cam means carried by said rod adapted for actuating said first switch in response to a to actuate said indexing means at the initiation of each retraction stroke; and means responsive to a predetermined pressure on said advancing means for rendering said first electrical means lnilective. V 4

7. In a hydraulic system; a reciprocable plunger having advancing and retracting means, first and second control means operable to direct actuating fluid to said advancing means or to said retracting means, respectively; a pair of spaced means operated respectively by said plunger at the end of the retraction stroke and at the end of the advancing stroke for automatically making first one and then the other of said control meanseffective for automatically reciprocating said plunger between predetermined limits; and means responsive to the initiation of the retraction stroke of said plunger for adjusting both of said spaced means a predetermined distance in said advancing direction.

8. In a hydraulic system; a reciprocable plunger having advancing and retracting means, first and second control means. operable to direct actuating fluid to said advancing means or to said retracting means, respectively; a pair of spaced means operated respectively by said plunger at the end of the retraction stroke and at the end of the advancing stroke for automatically making first one and then the other of said control means efiectlve for automatically reciprocating said plunger between predetermined sive means'connected with said retracting means operable in responseto a predetermined pressure on said retracting means for rotating said rod through a predetermined angle to adjust the abutment means carried thereby a predetermined limits; and means operable automatically following the end of one working stroke and prior to the end of the following retraction stroke for adjusting both of said spaced means a predetermined distance in said advancing direction.

. ROBERT A. KASER.

REFERENCES crrnn The following references are of record in the fiie of this patent:

UNITED STATES PA'I'ENTS Number Name Date 2,273,721 Muller Feb. 17, 1942 1,911,138 Clute May 23, 1933 2,283,356 Ernst May 19, 1942 2,324,727 Shartle July 20, 1943 2,222,732 Wlnegar Nov. 26, 19 .0 2,232,103 Ernst Feb. 18, 1941 1,927,583 Ernst Sept. 19, 1933 

